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From traflm <...@git.apache.org>
Subject [GitHub] incubator-trafodion pull request #664: TRAFODION-2163 support MYSQL style fu...
Date Fri, 19 Aug 2016 07:04:33 GMT
GitHub user traflm opened a pull request:

    https://github.com/apache/incubator-trafodion/pull/664

    TRAFODION-2163 support MYSQL style function GROUP_CONCAT

    add new SQL syntax for pivot_group() so to allow same MySQL syntax.
    Also fix original pivot_group() issue and tested more.
    But still protected by CQD mode_special_4, since we still need more tests. So by add this
MySQL syntax, we can test more real cases simpler, without modify the query to use pivot_group()
    
    The original pivot_group() has issue when rows are not sorted, its internal pointers to
track each bucket's len and pos is shared. One simple fix is to disallow hash groupby for
pivot_group, which used in this PR.
    A more complex and final fix will be to use bucket's own var for len and pos, but that
needs much more modification to current groupby which never need per bucket vars, and that
is only for pivot_group. So I would like to fix that later, and also need to implement the
sort direction support. 
    
    But this will make some real case to be supported and will simplify further tests, and
can already support most commonly used CONCAT_GROUP scenarios we saw previously.  

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/traflm/incubator-trafodion TRAFODION-2157

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-trafodion/pull/664.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #664
    
----
commit 1696410e6bff746a3f64ec1574f20fc0bbb93376
Author: Liu Ming <ovis_poly@sina.com>
Date:   2016-08-19T06:11:27Z

    TRAFODION-2163 support MYSQL style function GROUP_CONCAT

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